Blower apparatuses have been conventionally known and used for blowing off fallen leaves on the ground or the like. An example of blower apparatuses is disclosed in JP 2013-245,570 A, in which the blower apparatus comprises a blower unit mounted on a back carrier frame and a blow-off tube connected to the blower unit, and blows out air from the distal open end of the blow-off tube to blow off fallen leaves on the ground or the like. In a conventional configuration, however, the profile of the jetting-out airflow depends simply on the diameter of the open end of the blow-off tube, and the breadth of the jetting-out airflow is accordingly limited to a certain narrow extent. In case a broader airflow (air jet) is wanted, a nozzle tube having a larger outlet diameter may be attached to the distal end of the blow-off tube to produce a broader air jet output. However, attaching a larger size nozzle tube would make the apparatus bulky and worse-looking.